Heat transfer apparatus



Dec .5, 1933. OAKEY v 1,937,713

' 7 HEAT TRANSFER APPARATUS Filed April 26,. 19:50 2 sheets-sheet 2 II In \T Patented Dec. 5, 1933 PATENT OFFICE UNITED STATES near mansrsa APPARATUS H 7 William E. Oakey, Oriskany, N. Y., assignor to Revere Copper and Brass Incorporated, a corperation of Maryland Application April 2c. 1930. semi rim. M7571 id Glaims.

invention relates to heat transfer apparatus and has for its object the provision of an improved heat transfer apparatus of the sheet metal type. Such apparatus commonly emhod-" a ies a primary heat transfer element directly aflected by the heating or cooling medium and a secondary heat transfer element thermally associated with the primary element and adapted to facilitate the contemplated heat exchange.

Thus, in sheet metal radiators for heating systems, the primary element may be made up of a pair of stamped metal sections, such as sheet brass, welded together to provide an interior chamber for a heating or cooling fluid, and the secondary element may consist of fins of thin sheet metal such as copper, brass, etc., attached to the primary element. The particular aim of the present invention is to provide an improved radiator of this type capable of being economically manufactured and possessing relatively high heat transfer capacity. While the invention is especially applicable to radiators for heating systems, it may be advantageously embodied in coolers, condensers, refrigerators and other heat .5 transferdevices. i v The novel and improved features of the invention will be best understood from the following description taken in conjunction with the accompanying drawings, in which 39 Fig. 1 is a perspective view of a completed radiator embodying the invention;

Fig. 2 is a side elevation of the primary sheet metal element of the radiator,

Fig. 3 is a cross section in perspective of the a primary element;

Fig. 4 is a detail cross section taken on the section line H of Fig. '2; i

Fig. 5 is a detail perspective view. ofa multiple unit radiator of the invention, and

Fig. B-is a perspective view of the radiator of the invention connectedin one of its advantageous positions of use.

The improved radiator, or other heattransfer apparatus, of the invention comprises an elon- 5 gated primary heating or heat transfer element A, made up of a pair of complementary sheet metal half sections 10 and ll welded together at their edges 12 and also welded medially (13) to provide a plurality of adjacent chambers 14 lo communicating with one another at their ends. I

A secondary heat transfer element B is attached to each face of the primary element A. In the preferred formof the invention, each element B is made of a continuousmetal strip attached at It intervals to the primary element and bent repeatedly hack and forth to provide a plurality of relatively long and narrow box-like passages of which alternate-passages are closed on all sides but open at both ends while the other passages (20') are open on the outer side and at both ends. The heating or cooling fluid is ad- 'mitted to and exhausted from the chambers of the primary element through coupling C communicating with an appropriate source or supply of the heating fluid, such as steam, or of the cooling fluid where the apparatus is used for cooling and the like.

The half sections 10 and 11 are similarly stamped from appropriately shaped pieces of sheet metal, such as brass, copper or othermetal of good heat conductivity. In stamping, a plurality of longitudinally extending parallel recesses or troughs are formed in each half section (six in the apparatus illustrated in the drawings) terminating at each end in a common recess or manifold. When paired for assembly, the circumferential edges of the complementary half sections and the medial portions between the longitudinal recesses lie in substantially the same plane and in contact with one another. At each end, the half sections 10 and 11 have registering apertures 15 through which extend the threaded ends 16 of a nipple having an enlarged central portion 1'7 loosely confined between the sections. The enlarged portion of the nipple has one or more ports 18 providing communication with the hollow interior of the assembled primary element. The nipple may, if desired, be

made of two parts loosely .tied together, as described in the pending application of A. H.

Hart, Serial No. 207,529, filed July 21, 1927. The

half sections are welded together, preferably by continuous electric spot welding, along the edge 12 and medially along the contacting portions 13 between adjacent recesses.

The recesses in the half sectionslO and 11 are of such shape that the primary heating (or cooling) chambers 14 are flat walled. Thus, in

cross section (Fig. 3) the chambers 14 are of substantially hexagonal configuration, having relatively wide and flat opposite sidewalls, the

flat exteriors of which are in substantially the same plane and provide an admirable fiat surface for the attachment by soldering or otherwise of the secondary heat transfer elements B. The secondary heat transfer element 8 is. preferably made of a. continuous strip of copper, brass or other metal ,of good .heat conductivity.v This metal, strip is-bent repeatedly back and forth to provide a plurality of extended heatn transfer surfaces or fins 19. In the preferred form, the fins are parallel and equally spaced apart and provide a plurality of relatively long and narrow passages (20 and 20') alternately open on their narrow sides. The bending of the metal strip may advantageously be effected continuously by an automatic die.

The appropriately formed heat transfer elements B are attached to each of the substantially flat sides of the elongated primary element A with the fins 19 disposed transversely of the unit and extending rectangularly therefrom. This attachment is preferably accomplished by soldering. This may be advantageously carried out by solder-coating the flat edges on one side of the element B and maintaining the soldercoated edges incontact with the face of the primary element A under appropriate conditions of temperature and pressure.

The solder-coating of the edges of the element B may conveniently take place as each edge'emerges from the continuously operating forming die, whereupon the elements may be cut in lengths suitable for assembly on the primary element A. The elements B are then assembled on each side of the element A, and the assembly subjected to appropriate pressure and heating, localized as far as possible to the juncture of the element edges with the contacting flat sides of the primary element A.

The secondary heat transfer element B extends the entire length of the primary element A, and fins 19' approximate the couplings C being of appropriately reduced length. The shorter end flns'19' may be separately formed and assembled on the element A in separate sections. The provision of fins throughout the entire length of the primary element gives the maximum amount of extended heat transfer surface and avoids the existence of any open space or spaces of low frictional resistance through which air (or other medium to be heated or cooled) might pass or be short-circuited in preference to the contemplated passage of such air (or other medium) through the relatively long and narrow passages (20 and 20) of the heat transfer element B.

It is preferable in practice to construct the apparatus of one or more standard size units and to assemble two or more of these standard units in suitable groups where greater heating (or cooling) capacity is required. Thus, in Fig. 5 of the drawings, two standard size units are assembled side by side and interconnected by a IT-shaped coupling C threaded on the adjacent nipples (16), the other or outside nipples being closed by caps D. Various other groupings and interconnections of standard size imits may be made to meet particular requirements.

When constructed for use as a radiator in a heating system, the apparatus of .the invention is particularly adapted to be placed in narrow recesses as illustrated in Fig. 6 of the drawings. The recess 22 is in the wall of the room, say beneath a window frame 23. The radiator is installed near the bottom of the recess with its long dimension substantially parallel to the floor.

. The recess be lined with heat insulating material such as sheet asbestos and faced with sheet metal. The recess is provided-with a front plate 24 having an opening 25 near the floor and an opening or grille 26 at the top. The enclosure acts as a stack or flue, within which a positive movement of heated air is induced and diffused through the grille 26 into the room with sumcient velocity to insure uniform heating.

The passages 20 and 20' are vertically disposed to permit the free flow of air therethrough, and since they extend throughout the entire length of the radiator, all of the air flowing upwardly through the recess is uniformly heated.

It is characteristic of the apparatus of the invention that the contemplated heat exchange is effected for the most part by convection as distinguished from radiation. Thus, the primary and secondary elements are in intimate thermal relation with one another, and the flow or exchange of heat from one element to the other is effected at relatively high efliciency. The secondary element transmits or dissipates its heat (in the case of a radiator) to convection air currents induced to flow in direct contact with the extended heat transfer surfaces of that element by the'chimney effect resulting from the characteristic construction and positioning of the apparatus. Thus, in a radiator of the in-' vention, under favorable conditions of use, something over of the heat is given off or transmitted by means of convection rather than by radiation. This is a characteristic feature of the apparatus of the invention, whether constructed particularly as a radiator or for other heat transfer or exchange purposes.

The flat walled chambers 14 of the primary element A give an exterior surface with a substantially straight line contact for the straight 103 edges of the continuous box+-like fins of the secondary element B, thus providing a more or less ideal condition for the soldering or sweating operation. The fiat walled configuration of the chambers 14 gives increased cross sectional area, as compared with the oval configuration heretofore used in certain types of thin walled radiators. The oval configurationpresents a diaphragm-like surface to the internal pressure with a resultant tendency to bulge. The flat lit walled configuration possesses greater rigidity and structural strength and is much more resistant to such deformation.

I claim:-

1. The combination with a sheet metal heat transfer element having an interior multi-channeled chamber, of a plurality of spaced box-like heat transfer elements disposed transversely of and permanently bonded at intervals only to I exterior opposite faces of said sheet metal ele- 128 ment, said exterior faces being fiat where the box-like heat transfer elements are attached to insure adequate contact for optimum heat transfer.

2. The combination with an elongated sheet 130 metal heat transfer element having an interior multi-channeled chamber, of a continuous metal strip permanently bonded only at intervals to opposite sides of said element and bent repeated 1y back and forth to provide a plurality of extended heat transfer surfaces disposed transversely of and projecting from said element, said continuous metal strip havingflat contact faces adapted to be attached-to fiat exterior faces of' the sheet metal heat transfer element to insure 14C adequate contact for optimum heat tra: fer.

3. The combination with a primary sheet metal heat transfer element having an interior multi-chaimeled chamber for a heating or cooling fluid, of a continuous metal strip attached 148 only at intervals to opposite sides oi said element and bent repeatedly back and forth to provide a plurality of extended and spaced heat transfer surfaces, said continuous strip having flat contact faces adapted to be attached to flat exterior 15 faces of the sheet metal heat transfer element to insure adequate contact for optimum heat transfer. j

4. The combination with a primary sheet metal heat transfer element having an interior multi-channeled chamber for a heating or cooling fluid, of a secondaryheat transfer element only at intervals attached to said primary element and providing a plurality of relatively long and narrow passages of which alternate passages are closed on all sides but open at both ends while the other passages are open on the outer side and at both ends, said primary sheet metal heat transfer element and said secondary heat transfer element-being attached to one another along flat contact faces -to insure adequate contact for optimum heat transfer.

5. The combination with an elongated sheet metal heat transfer element having an interior multi-channeled chamber, of a continuous metal strip attached only at intervals to a side of said element and bent repeatedly back and forth to provide a plurality of heat transfer fins disposed transversely of and projecting substantially perpendicularly from the sides of said element, said continuous metal strip having fiat contact faces adapted to be attached to flat exterior faces-of the sheet metal heat transfer element to insure adequate strength for optimum heat transfer.

6. The combination with a primary sheet metal heat transfer element having an interior multi-channeled chamber for a heating or cooling fluid, of a secondary heat transfer element only at intervals attached to said primary element and made of a continuous metal strip bent repeatedly back and forth to provide a plurality of relatively long and narrow passages of which alternate passages are closedon all sides but open at both ends while the other passages are open on the'outer side and at both ends, the continuous metal strip of said secondary heat transfer element having flat contact faces adapted to be attached to fiat exterior-faces of said primary sheet metal heat transfer element to insure adequate contact for optimum heat transfer.

, '7. Thecombination with an elongated sheet metal heat transfer element having an interior chamber and a coupling at at least one of the ends communicating with said chamber, of a plurality of extended and spaced heat transfer fins disposed transversely of and attached to each face of said element throughout its entire length, the fins approximate said coupling or couplings'being of reduced length, said extended and spaced heat transfer fins having flat contact faces adapted to be attached to fiat exterior faces of said elongated sheet metal heat transfer element to insure adequate contact for rality of relatively long and narrow passages disposed transversely of the primary element with alternate passages closed on all sides but open at both ends and the other passages open on the outer side and at both ends, the passages approximate said coupling or couplings being of reduced length, said primary and secondary heat transfer elements being Joined together metal primary heat transfer element having a hollow interior divided into a plurality of longitudinally extending and substantially fiat walled chambers, of a secondary heat transfer element attached to each face of said primary element and providing a plurality of relatively long and narrow passages disposed transversely of the primary element with alternate passages closed on all sides but open at both ends and the other passages open on the outer side and at both ends, said secondary heat transfer element having flat contact faces adapted to be attached to the fiat walled chambers of said primary heat transfer element to insure contact for optimum heat transfer. I

10. The combination with a pair of elongated and complementary sheet metal sections welded together toform a primary heat transfer ele-- ment having a hollow interior divided into a plurality of longitudinally extending flat walled chambers, of a secondary heat transfer element attached to each side of said primary element and made of acontinuous metal strip bent back and forth to provide a plurality of relatively long narrow passages disposed: transversely of the primary 1 element, the continuouametal strip of said secondary heat transfer element having attached to each of the substantially flat sides of 11-5- said primary element and blade of a continuous metal strip bent back and forth to provide a plurality of equally spaced and parallel heat transfer fins disposed transversely of and projecting substantially perpendicularly from the sides of the primary element, the continuous metal strip of said secondary heat; transfer element having fiat contact faces adapted tobe attached to the flat walled elements of said secondary heat transfer element to insure adequate contact for optimum heat transfer.

12. The combination with a pair of elongated and complementary sheet metal sections welded together to .form a primary heat transfer element having a hollow interior divided into a plurality of longitudinally extending flat walled chambers for a heating or coolingffluid and a coupling at at least one of the ends providing communication with said chambers, of a. secondary heat transfer element attached to each of the substantially flat sides of said primary element and extending the entire length thereof and made of one or more metal strips bent back and forth to provide a. plurality of equally spaced and parallel heat transfer fins disposed transversely of and projecting substantially perpendicularly from the sides of the primary element, the fins approximate said couplingor couplings being of reduced length, said primary and secondary heat transfer elements being attached to one another along fiat faces to insure adequate contact for optimum heat transfer.

13. The combination with a sheet metal heat transfer element having an interior chamber sub-divided into a number of interconnecting passageways extending lengthwise oi the chamber proper for the free passage therethrough of a fluid, of a plurality of spaced box-like heat transfer elements disposed transversely of and permanently bonded at intervals only to exterior opposite faces of said sheet metal element, said exterior faces being flat where the box-like heattransfer elements are attached to insure adequate contact for optimum heat transfer.

14. A heat exchange apparatus comprising a 

